The present invention relates to self-sealing containers, and, more particularly, to containers constructed from two deformable sheets of material sealed together on all four sides to form a reservoir for containing fluid. The container is provided with an exit flow channel which leads from the reservoir to a terminal point near one of the sealed sides of the container. The fluid can be accessed by tearing or cutting the sealed edge to expose an orifice in the channel and by applying pressure to the container to expel its contents Once the pressure on the container is released, the exit flow channel seals itself automatically to prevent further egress of fluid.
Containers of all shapes, sizes and materials are extremely prevalent in our society. This is particularly true for packaging used to contain a variety of fluids, such as beverages, medicines, chemicals, etc. It is a consistent desire of manufacturers to reduce the cost of the container, which oftentimes exceeds the cost of its contents. Reusable containers are usually deemed to be cost prohibitive because of the cost of recycling or resterilization. Thus, there is a tendency for manufacturers to prefer disposable containers, not only for cost reasons, but also for health and safety reasons.
One type of disposable container, which is inexpensive to manufacture, takes the form of a pouch formed by two flexible sheets of material formed together around the periphery. The user simply tears or cuts one side of the pouch to access an exit flow channel, and the contents are expelled by manual pressure. Such flexible pouches are common for single-serving fluids such as condiments. However, for multiple-use fluids, such as beverages, these types of pouches are generally undesirable because of their inability to reseal at the exit flow channel once it is opened by the user. Thus, some manufacturers have attempted to produce flexible pouches which have sufficient rigidity or structure to permit them to stand erect in order to avoid spills or leakage. However, such additional features increase the cost of these types of packages. Other manufacturers have attempted to provide means for resealing the exit flow channel by providing various mechanical sealing elements (such as a duckbill valve) which bias the lips of the exit flow channel together to retain the fluid inside. Again, these additional features increase the cost of the packaging and have largely proven unsuccessful.
It has been suggested that the cost of such flexible packages can be greatly reduced by providing an exit flow channel which is automatically self-sealing. In other words, as soon as the expulsion pressure acting on the container is released or sufficiently reduced, the exit flow channel will automatically self-seal in order to prevent further fluid flow out of the package. Thus, leakage, spills or spoilage of the package contents can be avoided. This automatic self-sealing would obviously be a significant advantage in both single-use and multiple-use packages.
Previous attempts to produce a self-sealing exit flow channel have largely not been successful, especially in packaging which has actually been introduced in the commercial context. Essentially, previous manufacturers of such flexible packaging have attempted to design exit flow channels having a particular path geometry in order to accomplish self-sealing. In particular, the path geometry has been quite tortuous, consisting of channels which have, for example, S-shaped or hair pin turns. Other channels turn back toward the pouch reservoir or fold back on themselves in a Z-fold fashion. In other words, previously, it was thought that self-sealing was virtually wholly dependent on the shape of the path followed by the exit flow channel.
Not only was this design concept largely unsuccessful, but it also introduced many limitations in the applications in which such packages could exist. For example, with this previous approach, the orientation or direction of the exit flow channel could not be varied according to the specific use of the contents of the package. The exit flow channel would follow the same path whether the package contained a beverage, which would be consumed, or an industrial chemical, which might be applied to a machine. Furthermore, the orientation of the container (for example, in an upside down or sideways fashion) could not be varied to facilitate its use. Moreover, even if a self-seal could be accomplished, there was no flexibility in the design of previous containers to vary the flow rate of the fluid.
Thus, there has not been demonstrated in the prior art a complete understanding of the fluid dynamics associated with such containers having deformable sides, and, in particular, of the parametrical relationships in such self-sealing arrangements.